1. Technical Field
The invention relates to vehicle tires, and in particular to the marking of tires to satisfy governmental requirements and to provide additional inventory and historical data pertaining to each individual tire.
2. Background Information
Vehicle tires, particularly those intended for highway use, are required to be marked with certain data on the exterior of one of the sidewalls, generally adjacent the bead area of the tire, by the Department of Transportation (DOT) in human visible and readable characters. Heretofore, the data that was required to be molded on the sidewall consisted of the particular plant code in which the tire is manufactured, the tire size, tire line or type of tire, and week and year the tire was molded. This coded information, in the form of human readable numerals and/or letters, was easily applied to the tire during molding by placement of engraving strips on the inside of the tire curing mold. These code designations did not change appreciably, and thus was not difficult to incorporate into the curing mold for subsequent embossing or depressing into the sidewall of the cured tire. However, recent governmental legislation requires that complete DOT information, including the week and year in which the tire is molded, be molded on the intended outboard sidewall of the tire, and that partial DOT information (complete DOT less the week and year of molding) be molded on the external surface of the intended inboard sidewall of the tire. The addition of this DOT data and placement on both the inboard and outboard sidewalls of the tire will increase the cost of the tire molding or curing operation, especially for certain types of molds due to the constant replacement of the engraving strips or plugs in the mold each week on each press, and the difficulty of placing such information in the molds for molding on the intended outboard sidewall of the tire for certain types of molds.
In addition to marking vehicle tires with the required DOT data, it has become desirable to mark each tire with its own specific serial number, as well as additional manufacturing information pertaining to the tire for use in inventory control, warranty verification, customer satisfaction, and counterfeiting problems. However, the placement of such additional tire data on the sidewall of the tire increases the cost of producing the tire by the insertion and removal of the engraving strips in the curing presses or subsequent application of bar code strips on the tire, or electronic identification chips inside the tire. Also, it is desirable to be able to place much of this additional information or data on the tire in a non-human visible form and in an unobtrusive form so as not to distract from the appearance of the sidewall. However, it is necessary that this can be easily retrieved by machine readable retrievers for storage in a database or printable in hardcopy, yet which cannot be readily obtained by unauthorized sources.
Another problem that exists with the marking of tires by engraving or embossing the information thereon is that over the life of the tire, a portion of this data can become illegible due to wear and tire damage, preventing the desired data to be subsequently retrieved from the tire, especially as the tire ages.
However, recent developments in data encoding, referred to generally as encoded or 2D matrix symbology, enables a considerable amount of data to be placed on a surface of an object in a very unobtrusive manner, and which may be machine readable, even after a portion of the encoded data has been damaged or destroyed on the article. One such type of encoded symbology is the use of glyphs in a self-clocking glyph code. U.S. Pat. No. 6,076,738 discusses many features of this self-clocking glyph shaped codes and its manner of application and retrieval from an object. Another type of 2D encoding is referred to under the trademark DATA MATRIX.